825 replies to this topic

[speedengineer]

I'm not sure if this helps at all. And I think there's a pic out there too I'm looking for in the Fastracks after this (may)

http://mazdaracers.c...ge-1#entry77329

 

J~

 

Thanks much!  That does help a bit.  Nice that it defines the inside corner (tool) radius.  Still a bit confused as to: 

There must be a sharp, non-modified and non de-burred edge where the valve relief cut first meets the chamber.

 

So they added a word ..."valve relief cut [first] meets the chamber" but I still don't know that means based off text. 

 

 

 

Here's a clarification
http://cdn.growasset....pdf?1441316758

J~

This appears to be about the plunge cut.  They did a great job with the wording here, I think.  Pretty explicit what can be done. 

[Johnny D]

I'm not sure if you heard about the Runoffs last years, it hit the fan.
 
Here's another on page 3.

 

**Be careful you have the latest info since things were changed a bit (tuned) from month to month around this time.**

http://cdn.growasset....pdf?1434725484

 

J~
 

[speedengineer]

I'm not sure if you heard about the Runoffs last years, it hit the fan.
 
Here's another on page 3.

 

**Be careful you have the latest info since things were changed a bit (tuned) from month to month around this time.**

http://cdn.growasset....pdf?1434725484

 

J~
 

Everyone heard about runoffs last year 

 

Perfect, that's the diagram I needed, thank you!  According to that diagram, it appears it is acceptable to perform the relief cut all the way down to the surface of the valve seat.  Someone please correct me if this conclusion is incorrect. Note that for heads where the valve seat is sunk below the surface of the chamber, this will result in a ring of machined aluminum around the circumference of the valve seat.

 

 

 

 

Perhaps the sentence "There must be a sharp, non-modified and non de-burred edge where the valve relief cut first meets the chamber." is referring to prohibiting people from blending this edge?  Wording could probably be more concise, and a diagram or photo is worth a thousand words in this case...

 

[dstevens]

A pedigreed race car is more than the value of the the sum of the parts.  It's the experience for which you pay. (and to a lessor extent the physical labor)  Anyone that is building these for a living isn't going to part with that knowledge on a forum much less for free.

 

I'd buy a used legal SM race head from a known vendor.  Or perhaps even an entire engine.  From there you can either run it or tear it down and use what you learn to build another. Or both.  Either way a competitive engine isn't going to be built first time out by non SM builders.

 

It's great you are documenting you r build and doing most of it yourself.  I love working on cars and seeing a build come together.  The thread is going to be a great resource for those presently building cars.

[speedengineer]

A pedigreed race car is more than the value of the the sum of the parts.  It's the experience for which you pay. (and to a lessor extent the physical labor)  Anyone that is building these for a living isn't going to part with that knowledge on a forum much less for free.

 

I'd buy a used legal SM race head from a known vendor.  Or perhaps even an entire engine.  From there you can either run it or tear it down and use what you learn to build another. Or both.  Either way a competitive engine isn't going to be built first time out by non SM builders.

 

It's great you are documenting you r build and doing most of it yourself.  I love working on cars and seeing a build come together.  The thread is going to be a great resource for those presently building cars.

 

LOL Dave.

 

I am not asking which version is better performing nor any other sort of trade secret.  I am asking 'what is legal'.  Big difference!!

 

The rules should be clear such that anyone building a motor can comprehend them.  Same goes for any tech official - they need to be able to know what is legal without the need to "consult an expert'.  I am asking for rules clarification, not trade secrets.  The train of thought that "only the engine builders know what's legal and know how to interpret the rules" is what got SM into the 2014 Runoffs mess in the first place. 

 

I want to ensure that my build is 100% legal.  Please help me to accomplish that.  It may not make the most power, but I want it to be legal.  Make sense?

[Bench Racer]

One of the issues that has gotten into the process of SM engine build is the thought/words, standard machine shop practice. Oh a standard machine shop practice would be to smooth the edge from the plunge cut to the camber surface. Don't smooth the edge.

 

I've said it before and I'll say it again, when OEM aluminum heads are machined the left over/burr/flake removal is completed through a high pressure water wash.

 

Another issue is, it can't be measured. A great example of it can't be measure was the de-burring of the short turn radius. With a X power mirror and steel measuring scale it has been measure well enough to bust some folks.

[Jim Drago]

LOL Dave.

 

I am not asking which version is better performing nor any other sort of trade secret.  I am asking 'what is legal'.  Big difference!!

 

The rules should be clear such that anyone building a motor can comprehend them.  Same goes for any tech official - they need to be able to know what is legal without the need to "consult an expert'.  I am asking for rules clarification, not trade secrets.  The train of thought that "only the engine builders know what's legal and know how to interpret the rules" is what got SM into the 2014 Runoffs mess in the first place. 

 

I want to ensure that my build is 100% legal.  Please help me to accomplish that.  It may not make the most power, but I want it to be legal.  Make sense?

Jason

The relief cut can go down to seat. There can and will be a ring of aluminum removed around seat. The vertical wall of these cuts can not be radiused. You don't have to go to seat, you don't even have to choose to make those cuts. There is a radial dimension in the rules. I wont tell you what /how to do it. But there is little to no gain here and only gets you in trouble.. We stay .005 under the spec. The tool is bigger than spec by another .005/6. But I have seen the tool fall in holes that are to the spec. 

Let me know if that answers your question.. 

Jim

[speedengineer]

Jason

The relief cut can go down to seat. There can and will be a ring of aluminum removed around seat. The vertical wall of these cuts can not be radiused. You don't have to go to seat, you don't even have to choose to make those cuts. There is a radial dimension in the rules. I wont tell you what /how to do it. But there is little to no gain here and only gets you in trouble.. We stay .005 under the spec. The tool is bigger than spec by another .005/6. But I have seen the tool fall in holes that are to the spec. 

Let me know if that answers your question.. 

Jim

That answers it perfectly.  Thanks Jim, really appreciate it!

[speedengineer]

Check back soon for pics of cage build and more....I have the week off work so should be able to get a lot done.

 

For now, I spent a day getting the shop set up better.  Cleaning, organizing, and built a new workbench better suited for fabrication, and got the tubing bender and notcher set up.

 

 

 

 

I also ordered some replacement parts from Jim.  The fuel tank covers and the package shelf were corroded on my car due to a leaking soft top.  So, had to buy some used ones.  Granted, for used they look spotless, might as well have come from a new car.  I'm so jealous of all those who have access to miata salvage yards...!

[Steve Scheifler]

I have no idea how you can get anything accomplished amongst such chaos, at least tidy up a bit first!

My shop doubles as an obstacle and agility course to keep me in shape during the off season.

[speedengineer]

First off, whomever out there thought it was a good idea to red loctite the oem hardtop latches to the hardtop, including then stripping all the phillips heads, I hate you.  Must of been about an hour to get 5 of 6 screws out.  The 6th one sheared off... 

 

 

I've also been working on the cage. First step was to build the bases for the main hoop.  I am trying a new technique this year - drilling a hole in the top and dropping the main hoop through about a half inch.  Several reasons for this:

1. It's a pain to cut the bottom of the main hoop at the correct angle for a flush fitup, and also to achieve the exact clearance between the top of the hoop and the hardtop.  This method allows for easy setting of clearance, and perfect fitup.
2. This joint/weld is arguably the most important on the entire roll cage.  Passing the tube through the top plate means the plate itself is capable of supporting horizontal forces regardless of the weld.  Additionally, this method allows you to weld the tube to the plate on both the top and bottom of the plate.

 

 

 

 

Main hoop bent, tacked in place.  Diagonal brace also tacked in place.  The 'lil bar stock rear brace is there to stabilize the main hoop, as the actual rear braces are one of the last steps in the cage process.  This way I don't have to worry about accidentally breaking the main hoop tacks while I'm fitting up the front hoops, side bars, etc.

 

 

 

Not bad fitup for a holesaw tubing notcher.  For now I'm doing all the tacks with a MIG welder as I don't have my TIG machine on a cart I can roll around yet.  But, eventually I'll be TIG welding all the joints. 

[38bfast]

Heat the screws on the hardtop before you try and remove them and they will come out without issue.

Main hoop perches have marit.

[speedengineer]

Heat the screws on the hardtop before you try and remove them and they will come out without issue.

Main hoop perches have marit.

 

I tried as much heat as I dared to use, considering fiberglass, seemed to help a little bit.  I used heat, impact screwdriver, cut a slot in the screw for a flathead bit, more heat, penetrating oil, etc.  They were really in there!!

 

Thanks - yeah I can't think of any reason not to do the main hoop perches like that.  Seems like a win/win for both ease-of-fabrication and strength. 

[Bench Racer]

Neat/ingenious/ability to slide the main tube upward along with base horizontal plate taking the load without the weld.

 

%#@& hardtop latch screws and mine only had blue Loctite.

[Steve Scheifler]

I've got cars with the Miatacage version of perches on the floor, which are very similar but a bit smaller. I really like the design but unfortunately the perches and what that means in terms of main hoop vertical bar location make it impossible to install many popular seats near center and far enough back for tallish drivers.

[speedengineer]

I've got cars with the Miatacage version of perches on the floor, which are very similar but a bit smaller. I really like the design but unfortunately the perches and what that means in terms of main hoop vertical bar location make it impossible to install many popular seats near center and far enough back for tallish drivers.

 

What seats are those, Steve?  My last car I think I could have positioned the seat back as far as needed/practical.  Granted that was a pretty narrow seat, Recaro pro racer hans, non-xl version which only fits people with 32" waists or less. 

[Jim Drago]

I tried as much heat as I dared to use, considering fiberglass, seemed to help a little bit.  I used heat, impact screwdriver, cut a slot in the screw for a flathead bit, more heat, penetrating oil, etc.  They were really in there!!

 

Thanks - yeah I can't think of any reason not to do the main hoop perches like that.  Seems like a win/win for both ease-of-fabrication and strength. 

 

I have heated those SOB's with bright blue wrench before until I started smelling funny things. You have to heat further than you would like and then they thread out by hand, but you might not want to try as the bolts will be glowing orange when they come out

 

BTW it is -.5 sec not plus 5 MPH

[davew]

My procedure is listed in the book. Heat with propane or butane torch. Unscrew until binding, heat again, wash rinse repeat as needed. Usually take 3-4 heat/turn cycles. make sure to chase the threads before installing the brackets.

 

Dave

[Steve Scheifler]

What seats are those, Steve? My last car I think I could have positioned the seat back as far as needed/practical. Granted that was a pretty narrow seat, Recaro pro racer hans, non-xl version which only fits people with 32" waists or less.

None of the "containment" seats we have tried will fit for us without significant modification. That includes the Sparco Ergo, Momo (Daytona?) and Kirkey 70 series. We are 6'+ but under 190 lbs so these are not the large versions. Some are too wide at the base and all interfere at the shoulder supports. Even if I were shorter and leaner I would no longer go to the floor with the hoop because it limits the resale market.

[chris haldeman]

None of the "containment" seats we have tried will fit for us without significant modification. That includes the Sparco Ergo, Momo (Daytona?) and Kirkey 70 series. We are 6'+ but under 190 lbs so these are not the large versions. Some are too wide at the base and all interfere at the shoulder supports. Even if I were shorter and leaner I would no longer go to the floor with the hoop because it limits the resale market.

Tunnel notch panel helps a lot with those problems. Also for fia seats using a bracket that is a 90 deg bend at the bottom as apprised too the normal sparco type that bend out first allows the seat too be positioned another inch too the right helping with clearance. Biggest 2 guys I know are 6'5 220 and 6'2 220 both have the sparco pro adv with a Miata cage too the floor with out problems. Both cars have notch panels and straight sided 90 deg bottom brackets.